ROOF

PROBLEM TO BE SOLVED: To enhance bending rigidity and lighting by radially arranging a plurality of space truss beams, supporting a single layer truss positioned between the adjacent space truss beams on the space truss beam and constituting a roof of a truss dome. SOLUTION: A plurality of space truss beams 6 are radially arranged, a single layer truss 9 positioned between the adjacent truss beams is supported on the truss beam 6, and a roof is constituted of a truss dome. Next, the single layer truss 9 is supported on the radially arranged truss beam 6, it is reinforced and bending rigidity is improved while the single layer truss 9 is constituted as a main body. The structural characteristics of the dome is utilized to improve the rigidity of the truss beam 6 and the single layer truss 9, and when the truss beam 6 is constituted, the use number of the truss beams 6 is lessened. Thereby the obstruction of lighting by the truss beam 6 can be reduced to the minimum, and lighting can be enhanced while sufficient rigidity is secured.